\begin{tikzpicture}
    \draw (2, 0) circle [x radius=2, y radius=1];
    \node at (2, -1.5) {正数集合};
    \draw (8,0) circle [x radius=2, y radius=1];
    \node at (8, -1.5) {负数集合};
\end{tikzpicture}
